Hot-air stack.



A. G. SCHERER.

HOT AIR STACK.

APPUCATION FILED AUG-l0. 19x2.

Patented Mar. 14', 1916.

EFL? 15.55 E5 m (An THE COLUMBIA PLANOGRAPH (10., WASHINGTON. D c.

UNITED STATES PATENT clarion.

ALBERT G. SCHERER, OF CHICAGO, ILLINOIS, ASSIGNOR TO EXCELSIOR STEEL FURNACE COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

HOT-AIR STACK.

Specification of Letters Patent.

Patented Mar. 14, 1916.

Application filed August 10, 1912. Serial No. 714,351.

1 '0 all whom it may concern Be it known that I, ALBERT G. SGHERER, a citizen of the United States, and a resident of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Hot-Air Stacks, of which the following is a specification.

Hot air stack is employed for conveying hot air from a central plant or furnace to various portions of a building, and the present practice is to conceal it as much as possible, within the walls; and, on account of this practice, the stack is almost universally made of rectangular cross-sections so as to adapt it for installation between the stud ding, and at the same time secure the greatest cross-sectional area or capacity for carrying the air. Such stack is made of sheet metal with either double or single walls, the meeting edges of the necessary blanks of sheet metal being provided with reverse bends, which when assembled are pressed together thereby forming a joint the strength of which depends upon the thickness and toughness of the metal employed. Such stack, made in the usual manner, as above described, and having a rectangular cross-section, has little resistance to strains which tend to compress it; and, I have found that in both shipment and installation it has been so compressed, and the joints have been disengaged and the stack opened.

The object of my present invention is to stiffen the construction of such stack generally, and so form the seam or seams that they will not become disengaged and opened whether the pipe be compressed or not.

I attain the above objects by means of the construction illustrated in the accompanying drawing. in which Figure 1 is a perspective of a section of hot air stack embodying my present invention: Fig. 2 is a section on line 2-2 of Fig. 1; Fig. 3 is an enlarged fragmental section across the seam on line 3-3 of Fig. 1; and Fig. 4 is a view similar to that of Fig. 3 upon line 44 of Fig. 1.

Similar reference characters refer to similar parts throughout the several views.

The reference characters 1 and 2 designate respectively opposite broad sides of a section of rectangular hot air pipe which is formed of two sheets of metal. each of which are bent at right angles a suitable distance from their longitudinal edges to form the with each other and means for maintain ing the spacedrelation of the inner and outer walls are provided, but these form no part of my present invention, and need not be described.

With stack made in the usual way, as above described, the engaging reverse bends, 5 and 6, are compressed by a press or in any suitable manner, and it is these joints that are disengaged and forced open by compression of the stack, as above noted. In stack so made the three additional layers of metal at the seams form the ridge, or shoulder or seam, 9, which is usually thrown upon the outside of the stack. Now, in order to prevent the disengagement of this scam, I force, for short distances at suitable intervals, the shoulder 9 inwardly so that the outer surface thereof is substantially flush with the outer surface of the stack, and the seam projects on the inside of the stack, as shown at 10 in Fig. 1 and in Fig. 4 viewed in connection withFig. 3. This results in a I stiffening of the entire stack, and-prevents the disengagement of the reverse bends 5 and 6 by any pressure which would not be sufficient to wreck the entire structure.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is

1. A hot air stackof rectangular crosssection comprising a plurality of sheets of metal bent at right angles to form, when assembled, a conduit of rectangular cross-section, the meeting edges of said sheets being provided with engaging folds, said folds being compressed into a ridge. and separated and elongated sections of said ridge being forced to the side of the wall of each stack opposite to the side upon which the ridge was originally formed.

2. A double walled hot air stack of rectangular cross-section, comprising a plurality of sheets of metal bent at right angles to form, when assembled, a double Walled conduit of rectangular cross-section, the Walls whereof are spaced apart, the meeting edges of said sheets being provided with reverse engaging folds, said folds being compressed into a ridge, and separated elongated sections of said ridge being forced to the side of the Wall of each stack opposite to the side i0 upon which the ridge Was originally formed.

In testimony whereof I have hereunto set my hand in the pl'es'enceof two Witnesses.

ALBERT G. SCHERER.

llritnesses Jorm J. HALUB, BENJ. T; RoonHoUsE.

Copies of this patent may he obtained for five cents each, by addressing the-Commissioner of fiatents,

' Washington, D. 8. 

